Research On The Key Techniques Of Geometrical Simulation Of NC Milling On The Basis Of OpenGL

NC machining simulation is one of the basic key technologies of virtual manufacturing.NC machining simulation can accomplish the NC program verification,machining performance evaluating,loss reduction and development cycle shortening as well as test-cutting. But there still are problems of NC machining simulation.The paper studies on some key techniques of NC machining simulation.1.The paper constructs the model of the simulation system.Firstly,the paper analyses the geometrical structure and kinetic chain transferring and composition of the erect milling center on the basis of the hierachical structure,further more,sets up the geometrical and kinetic model.The paper applyes oop method and designs classes for the parts and components.These classes seals the geometrical and movement features and drawing of all the parts and components for the sake of modification and extention;On the basisof CSG method,the paper assembles all the parts and components according to the location and limitation relationship between them to form the integer model of the erect milling center and shows it on the screen dynamically. Secondly,the paper applyes zipvoxel model to workpieces and cutting tools to increase simulation speed which can reduce the three-dimensional boolean subtracting operation into one-dimensional.2. The paper carries out collision detection using octree and hierachical sphere compounding model algorithm.At first,the paper forms the octree and hierachical sphere compounding model;Second,the paper adopts linear octree method and introduces morton code to encode the address and gives the method to calculate the path according to Morton code.This method compresses the datum and save memory room.Third, the paper gives the detailed algorithm and reduces the redundancy operation to improve the detection speed.3.The paper completes the dynamic simulation of machining process of NC milling. First,the paper gives the general 5-parameter milling tool model and uses a simple and practical method to form the swept volume of milling tool;Second,the paper analyses all the phenomena of the boolean subtracting operation between two dexel chains. Third,the paper applyes the optimized MC method to pick up the triangle gridding on the surface and re-configure workpiece in OpenGL. Last, the paper implements the real-time displaying of NC milling process simulation dynamicly on the basis of OpenGL double buffer technique.